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Abstract:

An electrochemical cell is provided including, but not limited to, a can
having a side wall that is coupled to a first end and having a cover at a
second end of the can to close the second end of the can, a cell element
within the can, electrolyte within the can, and a safety device. The can
forms a vent at the first end configured to allow gases and/or effluent
to exit the can once the pressure inside the can reaches a predetermined
amount. The safety device is provided adjacent a first end of the cell
element and between the cell element and the first end of the housing.
The safety device is configured to exert an additional force on the vent
to aid in the deployment of the vent.

Claims:

1. An electrochemical cell comprising: a can having a side wall that is
coupled to a first end and having a cover at a second end of the can to
close the second end of the can, wherein the can forms a vent at the
first end configured to allow gases and/or effluent to exit the can once
the pressure inside the can reaches a predetermined amount; a cell
element within the can; electrolyte within the can; and a safety device
provided adjacent a first end of the cell element and between the cell
element and the first end of the housing, wherein the safety device is
configured to exert an additional force on the vent to aid in the
deployment of the vent.

2. The electrochemical cell of claim 1 wherein the can is cylindrical.

3. The electrochemical cell of claim 1 wherein the can is prismatic.

4. The electrochemical cell of claim 1, wherein the safety device exerts
enough force on the vent so as to fully separate the vent, during a high
pressure occurrence, from the bottom of the housing and interrupt any
current flowing through the cell.

5. The electrochemical cell of claim 1, wherein the safety device is a
compressive spring.

6. The electrochemical cell of claim 1, wherein the safety device is
coated with an electrically insulative material.

7. The electrochemical cell of claim 1, wherein the safety device is
configured to contain a suppressant to inhibit or limit the chance of a
flame when electrolyte is released from the cell.

8. The electrochemical cell of claim 7, wherein additional suppressant is
contained in a container or housing that is coupled to the outside of the
cell.

9. The electrochemical cell of claim 7, wherein a side wall of a housing
of the safety device extends generally along an entire length of a side
wall of the can.

10. The electrochemical cell of claim 9, wherein the housing of the
safety device includes a vent.

11. The electrochemical cell of claim 10, wherein the vent of the can may
be configured to deploy at a first pressure while the vent of the safety
device housing is configured to deploy at a second pressure that is
greater than the first pressure.

12. The electrochemical cell of claim 9, wherein the housing of the
safety device is made from an inert material.

13. The electrochemical cell of claim 1, wherein the side wall and the
first end are formed as a single unitary member.

14. The electrochemical cell of claim 1, wherein the side wall and first
end are formed as separate components that are later coupled together.

15. The electrochemical cell of claim 1, wherein the vent is formed at
the first end of the can.

16. An electrochemical cell comprising: a can having a side wall that is
coupled to a first end and having a cover at a second end of the can to
close the second end of the can, wherein the can forms a first vent at
the first end configured to allow gases and/or effluent to exit the can
once the pressure inside the can reaches a predetermined amount; a cell
element within the can; electrolyte within the can; and a safety device
in fluid communication with the first vent, wherein the safety device
houses a suppressant which inhibits or limits the chance of a flame when
electrolyte is released from the cell.

17. The electrochemical cell of claim 16 wherein the can is cylindrical.

18. The electrochemical cell of claim 16 wherein the can is prismatic.

19. The electrochemical cell of claim 16, wherein the electrochemical
cell is a lithium-ion cell, a nickel-metal-hydride cell, or a lithium
polymer cell.

20. The electrochemical cell of claim 16, wherein the safety device forms
a housing coupled to the can of the cell, and wherein the housing forms a
chamber in which the suppressant is contained.

21. The electrochemical cell of claim 20, wherein a side wall of the
housing of the safety device extends generally along an entire length of
the side wall of the can.

22. The electrochemical cell of claim 20, wherein the housing of the
safety device includes a second vent.

23. The electrochemical cell of claim 22, wherein the first vent of the
can may be configured to deploy at a first pressure while the second vent
of the safety device housing is configured to deploy at a second pressure
that is greater than the first pressure.

24. The electrochemical cell of claim 21, wherein the housing of the
safety device is made from an inert material.

25. The electrochemical cell of claim 16, wherein the side wall and the
first end are formed as a single unitary member.

26. A standby power unit comprising a battery system having the
electrochemical cell of claim 16, wherein the standby power unit provides
power which may be used as a substitute for power provided from an
electrical grid.

27. A method for controlling heat within an electrochemical cell, the
electrochemical cell having a can having a side wall that is coupled to a
first end and having a cover at a second end of the can to close the
second end of the can, wherein the can forms a vent at the first end
configured to allow gases and/or effluent to exit the can once the
pressure inside the can reaches a predetermined amount, a cell element
within the can, electrolyte within the can, and a safety device provided
adjacent a first end of the cell element and between the cell element and
the first end of the housing, the method comprising: exerting an
additional amount of force onto the vent by the safety device in order to
aid in the deployment of the vent.

28. The method of claim 27 wherein the can is cylindrical.

29. The method of claim 27 wherein the can is prismatic.

30. The method of claim 27, wherein the electrochemical cell is a
lithium-ion cell, a nickel-metal-hydride cell, or a lithium polymer cell.

31. The method of claim 27, wherein the additional amount of force onto
the vent is sufficient to fully separate the vent, during a high pressure
occurrence, from the bottom of the housing and interrupt any current
flowing through the cell.

32. The method of claim 27, wherein the safety device is a compressive
spring.

33. The method of claim 27, wherein the safety device is coated with an
electrically insulative material.

34. A method for controlling heat within an electrochemical cell, the
electrochemical cell having a can having a side wall that is coupled to a
first end and having a cover at a second end of the can to close the
second end of the can, wherein the can forms a first vent at the first
end configured to allow gases and/or effluent to exit the can once the
pressure inside the can reaches a predetermined amount, a cell element
within the can, electrolyte within the can, and a safety device provided
in fluid communication with the first vent, wherein the safety device
houses a suppressant which inhibits or limits the chance of a flame when
electrolyte is released from the cell, the method comprising: deploying
the first vent once the pressure inside the can reaches a predetermined
amount to allow gases and/or effluent to exit the can; and mixing the
gases and/or effluent released from the can with suppressant housed by
the safety device.

35. The method of claim 34 wherein the can is cylindrical.

36. The method of claim 34 wherein the can is prismatic.

37. The method of claim 34, wherein the electrochemical cell is a
lithium-ion cell, a nickel-metal-hydride cell, or a lithium polymer cell.

38. The method of claim 34, wherein the safety device forms a housing
coupled to the can of the cell, and wherein the housing forms a chamber
in which the suppressant is contained.

39. The method of claim 38, wherein a side wall of the housing of the
safety device extends generally along an entire length of the side wall
of the can.

40. The method of claim 38, wherein the housing of the safety device
includes a second vent.

Description:

RELATED APPLICATIONS

[0001] The present application is related to and claims benefit under 35
U.S.C. §119(e) from U.S. Provisional Patent Application Ser. No.
61/548,657, entitled, "ELECTROCHEMICAL CELL HAVING A SAFETY DEVICE,"
filed Oct. 18, 2011, the entire contents of which are hereby incorporated
by reference in their entirety to the extent permitted by law.

FIELD OF THE DISCLOSURE

[0002] The present application relates generally to the field of batteries
and battery systems and, more specifically, to batteries and battery
systems that may be used in vehicle applications to provide at least a
portion of the motive power for a vehicle using electric power.

BACKGROUND OF THE INVENTION

[0003] Vehicles using electric power for all or a portion of their motive
power may provide a number of advantages as compared to more traditional
gas-powered vehicles using internal combustion engines. For example,
vehicles using electric power may produce fewer undesirable emission
products and may exhibit greater fuel efficiency as compared to vehicles
using internal combustion engines (and, in some cases, such vehicles may
eliminate the use of gasoline entirely).

[0004] As technology continues to evolve, there is a need to provide
improved power sources (e.g., battery systems or modules) for such
vehicles. For example, it is desirable to increase the distance that such
vehicles may travel without the need to recharge the batteries. It is
also desirable to improve the performance of such batteries and to reduce
the cost associated with the battery systems.

[0005] One area of improvement that continues to develop is in the area of
battery chemistry. Early systems for vehicles using electric power
employed nickel-metal-hydride (NiMH) batteries as a propulsion source.
Over time, different additives and modifications have improved the
performance, reliability, and utility of NiMH batteries.

[0006] More recently, manufacturers have begun to develop lithium-ion
batteries that may be used in vehicles using electric power. There are
several advantages associated with using lithium-ion batteries for
vehicle applications. For example, lithium-ion batteries have a higher
charge density and specific power than NiMH batteries. Stated another
way, lithium-ion batteries may be smaller than NiMH batteries while
storing the same amount of charge, which may allow for weight and space
savings in a vehicle using electric power (or, alternatively, this
feature may allow manufacturers to provide a greater amount of power for
the vehicle using electric power without increasing the weight of the
vehicle using electric power or the space taken up by the battery
system).

[0007] It is generally known that lithium-ion batteries perform
differently than NiMH batteries and may present design and engineering
challenges that differ from those presented with NiMH battery technology.
For example, lithium-ion batteries may be more susceptible to variations
in battery temperature than comparable NiMH batteries, and thus systems
may be used to regulate the temperatures of the lithium-ion batteries
during vehicle operation. The manufacture of lithium-ion batteries also
presents challenges unique to this battery chemistry, and new methods and
systems are being developed to address such challenges.

[0008] It is also generally known that batteries and battery systems (both
lithium-ion and NiMH) are subjected to various environmental and other
potentially damaging conditions. For example, battery systems are
sometimes provided on the exterior or underside of a vehicle using
electric power, subjecting the battery systems to rain, snow, sleet and
any other combination of inclement weather. Such battery systems may also
be impacted by an object, such as, e.g., during an accident, which may
cause a short circuit condition of the battery. Further, abuse of a
battery (e.g., a short circuit, or over/under charging) may lead to high
temperatures and/or excess pressure within the battery, causing the
battery to vent electrolyte contained within the battery.

[0009] It would be desirable to provide an improved battery module and/or
system for use in vehicles using electric power that addresses one or
more challenges associated with NiMH and/or lithium-ion battery systems
used in such vehicles. It also would be desirable to provide a battery
module and/or system that includes any one or more of the advantageous
features that will be apparent from a review of the present disclosure.

SUMMARY

[0010] The present invention is defined by the following claims, and
nothing in this section should be taken as a limitation on those claims.

[0011] According to one aspect, an electrochemical cell is provided
including, but not limited to, a can having a side wall that is coupled
to a first end and having a cover at a second end of the can to close the
second end of the can, a cell element within the can, electrolyte within
the can, and a safety device. The can forms a vent at the first end
configured to allow gases and/or effluent to exit the can once the
pressure inside the can reaches a predetermined amount. The safety device
is provided adjacent a first end of the cell element and between the cell
element and the first end of the housing. The safety device is configured
to exert an additional force on the vent to aid in the deployment of the
vent.

[0012] According to one aspect, an electrochemical cell is provided
including, but not limited to, a can having a side wall that is coupled
to a first end and having a cover at a second end of the can to close the
second end of the can, a cell element within the can, electrolyte within
the can, and a safety device. The can forms a first vent at the first end
configured to allow gases and/or effluent to exit the can once the
pressure inside the can reaches a predetermined amount. The safety device
is in fluid communication with the first vent. The safety device houses a
suppressant which inhibits or limits the chance of a flame when
electrolyte is released from the cell.

[0013] According to one aspect, a method for controlling heat within an
electrochemical cell is provided. The electrochemical cell has a can
having a side wall that is coupled to a first end and having a cover at a
second end of the can to close the second end of the can. The can forms a
vent at the first end configured to allow gases and/or effluent to exit
the can once the pressure inside the can reaches a predetermined amount.
The electrochemical cell also has a cell element within the can,
electrolyte within the can, and a safety device provided adjacent a first
end of the cell element and between the cell element and the first end of
the housing. The method includes, but is not limited to, exerting an
additional amount of force onto the vent by the safety device in order to
aid in the deployment of the vent.

[0014] According to one aspect, a method for controlling heat within an
electrochemical cell is provided. The electrochemical cell has a can
having a side wall that is coupled to a first end and having a cover at a
second end of the can to close the second end of the can. The can forms a
first vent at the first end configured to allow gases and/or effluent to
exit the can once the pressure inside the can reaches a predetermined
amount. The electrochemical cell also has a cell element within the can,
electrolyte within the can, and a safety device provided in fluid
communication with the first vent. The safety device houses a suppressant
which inhibits or limits the chance of a flame when electrolyte is
released from the cell. The method includes, but is not limited to,
deploying the first vent once the pressure inside the can reaches a
predetermined amount to allow gases and/or effluent to exit the can, and
mixing the gases and/or effluent released from the can with suppressant
housed by the safety device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The invention can be better understood with reference to the
following drawings and description. The components in the figures are not
necessarily to scale, emphasis instead being placed upon illustrating the
principles of the invention.

[0016] FIG. 1 is a perspective view of a vehicle including a battery
system according to an exemplary embodiment.

[0017]FIG. 2 is a cutaway schematic view of a vehicle including a battery
system according to an exemplary embodiment.

[0018] FIG. 3 is a partial cutaway view of a battery system according to
an exemplary embodiment.

[0019]FIG. 4 is another partial cutaway view of the battery system of
FIG. 3 according to an exemplary embodiment.

[0020]FIG. 5 is a cross-sectional view of an electrochemical cell having
a safety device according to an exemplary embodiment.

[0021]FIG. 5A is a detail view a portion of the electrochemical cell of
FIG. 5 showing a vent partially open according to an exemplary
embodiment.

[0022]FIG. 5B is a detail view a portion of the electrochemical cell of
FIG. 5 showing a vent fully open according to an exemplary embodiment.

[0023]FIG. 6 is a cross-sectional view of an electrochemical cell having
a safety device according to another exemplary embodiment.

[0024]FIG. 7 is a cross-sectional view of an electrochemical cell having
a safety device according to yet another exemplary embodiment.

DETAILED DESCRIPTION

[0025] FIG. 1 is a perspective view of a vehicle 10 in the form of an
automobile (e.g., a car) having a battery system 20 for providing all or
a portion of the motive power for the vehicle 10.

[0026] For the purposes of the present disclosure, it should be noted that
the battery modules and systems illustrated and described herein are
particularly directed to applications in providing and/or storing energy
in xEV electric vehicles. As will be appreciated by those skilled in the
art, hybrid electric vehicles (HEVs) combine an internal combustion
engine propulsion and high voltage battery power to create traction, and
includes mild hybrid, medium hybrid, and full hybrid designs. A plug-in
electric vehicle (PEV) is any vehicle that can be charged from an
external source of electricity, such as wall sockets, and the energy
stored in the rechargeable battery packs drives or contributes to drive
the wheels. PEVs are a subcategory of vehicles using electric power for
propulsion that include all-electric (EV) or battery electric vehicles
(BEVs), plug-in hybrid vehicles (PHEVs), and electric vehicle conversions
of hybrid electric vehicles and conventional internal combustion engine
vehicles. The term "xEV" is defined herein to include all of the
foregoing or any variations or combinations thereof that include electric
power as a motive force. Additionally, although illustrated as a car in
FIG. 1, the type of the vehicle 10 may be implementation-specific, and,
accordingly, may differ in other embodiments, all of which are intended
to fall within the scope of the present disclosure. For example, the
vehicle 10 may be a truck, bus, industrial vehicle, motorcycle,
recreational vehicle, boat, or any other type of vehicle that may benefit
from the use of electric power for all or a portion of its propulsion
power.

[0027] For the purposes of the present disclosure, it should be also noted
that the battery modules and systems illustrated and described herein are
also particularly directed to applications in providing and/or storing
energy in stand-by power units which may be used to provide power for
residential homes or businesses which typically rely on power provided
from an electrical grid. A stand-by power unit can provide power which
may be used as a substitute for power provided from an electrical grid,
for any building or device which typically relies on power provided from
an electrical grid, such as a residential home or business.

[0028] Although the vehicle 10 is illustrated as a car in FIG. 1, the type
of vehicle may differ according to other exemplary embodiments, all of
which are intended to fall within the scope of the present disclosure.
For example, the vehicle 10 may be a truck, bus, industrial vehicle,
motorcycle, recreational vehicle, boat, or any other type of vehicle that
may benefit from the use of electric power for all or a portion of its
propulsion power.

[0029] Although the battery system 20 is illustrated in FIG. 1 as being
positioned in the trunk or rear of the vehicle, according to other
exemplary embodiments, the location of the battery system 20 may differ.
For example, the position of the battery system 20 may be selected based
on the available space within a vehicle, the desired weight balance of
the vehicle, the location of other components used with the battery
system 20 (e.g., battery management systems, vents, or cooling devices,
etc.), and a variety of other consideration.

[0030]FIG. 2 illustrates a cutaway schematic view of a vehicle 10A
provided in the form of an HEV according to an exemplary embodiment. A
battery system 20A is provided toward the rear of the vehicle 10A
proximate a fuel tank 12 (the battery system 20A may be provided
immediately adjacent the fuel tank 12 or may be provided in a separate
compartment in the rear of the vehicle 10A (e.g., a trunk) or may be
provided elsewhere in the vehicle 10A). An internal combustion engine 14
is provided for times when the vehicle 10A utilizes gasoline power to
propel the vehicle 10A. An electric motor 16, a power split device 17,
and a generator 18 are also provided as part of the vehicle drive system.

[0031] Such a vehicle 10A may be powered or driven by just the battery
system 20A, by just the engine 14, or by both the battery system 20A and
the engine 14. It should be noted that other types of vehicles and
configurations for the vehicle drive system may be used according to
other exemplary embodiments, and that the schematic illustration of FIG.
2 should not be considered to limit the scope of the subject matter
described in the present application.

[0032] According to various exemplary embodiments, the size, shape, and
location of the battery systems 20, 20A, the type of vehicles 10, 10A,
the type of vehicle technology (e.g., HEV, PEV, EV BEV, PHEV, xEV, etc.),
and the battery chemistry, among other features, may differ from those
shown or described.

[0033] Referring now to FIGS. 3-4, partial cutaway views of a battery
system 21 are shown according to an exemplary embodiment. According to an
exemplary embodiment, the battery system 21 is responsible for packaging
or containing electrochemical batteries or cells 24, connecting the
electrochemical cells 24 to each other and/or to other components of the
vehicle electrical system, and regulating the electrochemical cells 24
and other features of the battery system 21. For example, the battery
system 21 may include features that are responsible for monitoring and
controlling the electrical performance of the battery system 21, managing
the thermal behavior of the battery system 21, containing and/or routing
of effluent 25 (e.g., gases that may be vented from a cell 24), and other
aspects of the battery system 21.

[0034] According to the exemplary embodiment as shown in FIGS. 3-4, the
battery system 21 includes a cover or housing 23 that encloses the
components of the battery system 21. Included in the battery system are
two battery modules 22 located side-by-side inside the housing 23.
According to other exemplary embodiments, a different number of battery
modules 22 may be included in the battery system 21, depending on the
desired power and other characteristics of the battery system 21.
According to other exemplary embodiments, the battery modules 22 may be
located in a configuration other than side-by-side (e.g., end-to-end,
etc.).

[0035] As shown in FIGS. 3-4, the battery system 21 also includes a high
voltage connector 28 located at one end of the battery system 21 and a
service disconnect 30 located at a second end of the battery system 21
opposite the first end according to an exemplary embodiment. The high
voltage connector 28 connects the battery system 21 to a vehicle 10. The
service disconnect 30, when actuated by a user, disconnects the two
individual battery modules 22 from one another, thus lowering the overall
voltage potential of the battery system 21 by half to allow the user to
service the battery system 21.

[0036] According to an exemplary embodiment, each battery module 22
includes a plurality of cell supervisory controllers (CSCs) 32 to monitor
and regulate the electrochemical cells 24 as needed. According to other
various exemplary embodiments, the number of CSCs 32 may differ. The CSCs
32 are mounted on a member shown as a trace board 34 (e.g., a printed
circuit board). The trace board 34 includes the necessary wiring to
connect the CSCs 32 to the individual electrochemical cells 24 and to
connect the CSCs 32 to the battery management system (not shown) of the
battery system 21. The trace board 34 also includes various connectors to
make these connections possible (e.g., temperature connectors, electrical
connectors, voltage connectors, etc.).

[0037] Still referring to FIGS. 3-4, each of the battery modules 22
includes a plurality of electrochemical cells 24 (e.g., lithium-ion
cells, nickel-metal-hydride cells, lithium polymer cells, etc., or other
types of electrochemical cells now known or hereafter developed).
According to an exemplary embodiment, the electrochemical cells 24 are
generally lithium-ion cells configured to store an electrical charge.
According to other exemplary embodiments, the electrochemical cells 24
could have other physical configurations (e.g., oval, prismatic,
polygonal, etc.). The capacity, size, design, and other features of the
electrochemical cells 24 may also differ from those shown according to
other exemplary embodiments.

[0038] Each of the electrochemical cells 24 are electrically coupled to
one or more other electrochemical cells 24 or other components of the
battery system 21 using connectors provided in the form of bus bars 36 or
similar elements. According to an exemplary embodiment, the bus bars 36
are housed or contained in bus bar holders 37. According to an exemplary
embodiment, the bus bars 36 are constructed from a conductive material
such as copper (or copper alloy), aluminum (or aluminum alloy), or other
suitable material. According to an exemplary embodiment, the bus bars 36
may be coupled to terminals 38, 39 of the electrochemical cells 24 by
welding (e.g., resistance welding) or through the use of fasteners 40
(e.g., a bolt or screw may be received in a hole at an end of the bus bar
36 and screwed into a threaded hole in the terminal 38, 39).

[0039] Referring now to FIG. 5, a side cross-sectional view of an
electrochemical cell 24 having a safety device 33 is shown according to
an exemplary embodiment. The electrochemical cell 24 generally includes a
can or housing 23. The housing 23 includes a cylindrical side wall 27
that is coupled to a first or closed end 31 at a bottom 29 of the housing
23. According to one exemplary embodiment, the cylindrical side wall 27
and the first end 31 are formed as a single unitary member (i.e., the
side wall 27 and first end 31 are integral). According to another
exemplary embodiment, the side wall 27 and first end 31 are formed as
separate components that are later coupled (e.g., welded) together. A
cover or lid 35 is provided at a second end 41 of the housing 23 to close
the second end 41 of the housing 23.

[0040] According to an exemplary embodiment, a cell element 43 is provided
within the housing 23. The cell element 43 includes a negative electrode
(i.e., anode), a positive electrode (i.e., cathode), and at least one
separator provided between the negative electrode and the positive
electrode. According to an exemplary embodiment, the electrodes and
separators are wound around a central core or mandrel 42 (e.g., by using
a drive device 44 coupled to the mandrel 42) to form the cell element 43
(e.g., a wound, jelly-roll cell element).

[0041] It should be noted that those skilled in the art will readily
recognize that alternative cell configurations may be utilized. For
example, the cell 24 may be a prismatic cell having either a wound cell
element 43 or prismatic electrode plates. Further, the capacity, size,
design, and other features of the electrochemical cell 24 may also vary
depending on the specific requirements of the application.

[0042] According to an exemplary embodiment, the electrodes are arranged
offset from one another such that an edge of the positive electrode
extends out beyond a first end of the cell element 43 and an edge of the
negative electrode extends out beyond a second end 41 of the cell element
43. As such, each edge of each electrode may be conductively coupled to a
corresponding terminal (such as, e.g., a positive terminal 38 or a
negative terminal 39 as shown in FIG. 5).

[0043] According to the exemplary embodiment as shown in FIG. 5, the edge
of the positive electrode is conductively coupled to the first end 26 of
the housing 23 via a first connection strip or positive current collector
46. The first end 26 of the housing 23, in turn, is conductively coupled
to the cylindrical side wall 27 of the housing 23, which is conductively
coupled to the cover 35 at the second end 41 of the housing 23. The cover
35, in turn, is conductively coupled to the positive terminal 38. As
such, electrical energy is transferred to/from the positive electrode to
the positive terminal 38 (i.e., via the positive current collector 46,
second end 41 of the housing 23, side wall 27 of the housing 23, and
cover 35).

[0044] Likewise, according to the exemplary embodiment as shown in FIG. 5,
the edge of the negative electrode is conductively coupled to the
negative terminal 39 via a second connection strip or negative current
collector 48. The negative terminal 39 extends through an aperture or
opening 50 formed in the cover 35 and is electrically insulated from the
cover 35 by an insulator or gasket 52. As such, electrical energy is
transferred to/from the negative electrode to the negative terminal 39.

[0045] It should be noted that those skilled in the art will readily
recognize that alternative current collector and/or terminal
configurations may be utilized. For example, the current collectors 46,
48 may be eliminated with the terminals 38, 39 directly coupled to the
respective electrodes. Additionally, for example, terminals 38, 39 may be
disposed on opposite sides of the housing 23, multiple terminals 38
and/or 39 may be coupled to each electrode, terminals 38, 39 may have
different shapes, etc.

[0046] Referring to FIGS. 5-5B, according to an exemplary embodiment, the
cell 24 includes a vent 26. The vent 26 is configured to allow gases
and/or effluent 25 to exit the cell 24 once the pressure inside the cell
24 reaches a predetermined amount (e.g., during a rise in cell
temperature). When the vent 26 deploys (e.g., activates, opens,
separates, etc.), the gases and/or effluent 25 inside the cell 24 exit
the cell 24 in order to lower the pressure inside the cell 24 (e.g., as
represented by arrows shown in FIGS. 5A-5B). According to an exemplary
embodiment, the vent 26 acts as a safety device 33 for the cell 24 during
a high pressure occurrence. Preferably, a high pressure occurrence is a
condition when the pressure within the cell 24 reaches a predetermined
amount. Preferably, the predetermined amount is from 800 kPa to 1200 kPa,
and more preferably from 900 kPa to 1100 kPa, and most preferably at
least 900 kPa.

[0047] According to an exemplary embodiment, the vent 26 is located in the
bottom or bottom portion 29 of the housing 23. According to other
exemplary embodiments, the vent 26 may be located elsewhere (e.g., such
as in the lid or cover 35 of the cell 24). According to another exemplary
embodiment, the vent 26 may be located in a cover 35 or bottom 29 that is
a separate component from the housing 23 that in turn is coupled to the
housing 23 (e.g., by a welding operation).

[0048] According to an exemplary embodiment, the bottom 29 of the housing
23 may include a ridge, projection, or ring of material (not shown) to
prevent fracture of the vent 26 during handling and/or assembly of the
cell 24. The ring of material is intended to provide for a clearance
space between the vent 26 and a surface that the cell 24 is set upon.
According to an exemplary embodiment, the clearance space is configured
to prevent the vent 26 from being accidentally bumped (and deployed)
during handling and/or assembly of the cell 24.

[0049] According to an exemplary embodiment, the vent 26 includes at least
one annular fracture groove 54 (e.g., ring, trough, pressure point,
fracture point, fracture ring, thinned area, weakened area, etc.).
According to an exemplary embodiment, the annular fracture groove 54 has
a V-shaped bottom and is configured to break away (i.e., separate) from
the bottom 29 of the housing 23 when the vent 26 deploys. According to
other exemplary embodiments, the bottom of the annular fracture groove 54
may have another shape (e.g., rounded shape, curved shape, U-shape,
etc.). According to other exemplary embodiments, the annular fracture
groove 54 may include a weakened or thinned area 56 (i.e., area of
reduced thickness) at the bottom 29 of the housing 23.

[0050] As stated earlier, the vent 26 is configured to deploy once the
pressure inside the cell 24 reaches a pre-determined amount. When the
vent 26 deploys, the annular fracture groove 54 fractures and separates
the vent 26 from the rest of the bottom of the housing, allowing the
internal gases and/or effluent 25 to escape the cell 24 (e.g., as shown
in FIG. 24B). By having the vent 26 separate from the bottom 29 of the
housing 23, the vent 26 acts as a current interrupt or current disconnect
device. This is because the separation of the vent 26 from the bottom 29
of the housing 23 disrupts the flow of current from the cell element 43
(through the positive current collector) to the housing 23. In this way,
the vent 26 acts not only as an over-pressure safety device, but also as
a current disconnect device.

[0051] In order to help electrically insulate the bottom 49 of the cell
element 43 from the bottom of the housing, the cell 24 may include an
insulative member (such as, e.g., shown as gasket 51 in FIGS. 5-5B). As
shown in FIGS. 5-5B, the gasket 51 is provided adjacent the first end 31
of the housing 23 between the cell element 43 and the bottom 29 of the
housing 23. When the vent 26 is deployed, the gasket 51 provides
electrical insulation between the bottom 49 of the cell element 43 and
the bottom 29 of the housing 23 to ensure that there is no electrical
connection between the cell element 43 and the bottom 29 of the housing
23.

[0052] According to an exemplary embodiment, the vent 26 (e.g., the
annular fracture groove 54) is formed by tooling located external the
housing 23. The tooling tolerance is only affected by one side of the
tool, allowing for a more consistent annular fracture groove 54,
resulting in a more consistent and repeatable opening of the vent 26. The
depth, shape, and size of the fracture groove may be easily modified
simply by changing the tooling. Additionally, the vent 26 is easy to
clean and inspect since the vent 26 (and annular fracture groove 54) is
located on an external side of the housing 23.

[0053] According to one exemplary embodiment, the cell element 43 does not
move during deployment of the vent 26 (i.e., the cell element 43 remains
stationary). According to such an exemplary embodiment, the positive
current collector 46 is designed to be flexible (e.g., such as shown in
FIGS. 5A-B). According to other exemplary embodiments, the cell element
43 may move in order to help deploy the vent 26 (e.g., by "pushing" or
"punching" the current collector through the vent). According to such
exemplary embodiments, a non-flexible positive current collector 46 may
be utilized.

[0054] Still referring to FIGS. 5-5B, the electrochemical cell 24 includes
a first type of safety device 33 according to an exemplary embodiment. As
shown in FIGS. 5-5B, the safety device 33 is a spring 45 (e.g., a
compression spring), or a plurality of springs 45. However, according to
another exemplary embodiment, the safety device 33 may be a spring
washer. The safety device 33 is configured to aid in the deployment of
the vent 26.

[0055] According to the exemplary embodiment shown in FIGS. 5-5B, the
safety device 33 is provided adjacent the first end of the cell 24
between the cell element 43 and the bottom 29 of the housing 23.
Specifically, the safety device 33 is shown to contact the bottom 29 of
the housing 23 just inside the annular fracture groove 54 of the vent 26.
As such, the safety device 33 is configured to exert a force on the vent
26 to aid in the deployment of the vent 26.

[0056] As shown in FIG. 5A, the when the vent 26 initially deploys, the
vent 26 may only partially open (i.e., the vent 26 may only be partially
separated from the bottom 29 of the housing 23). The safety device 33 is
configured to exert a force on the vent 26 (e.g., around the
circumference of the vent 26) so that the vent 26 fully separates from
the bottom 29 of the housing 23. By fully separating from the bottom 29
of the housing 23, the current flowing through the cell 24 is
interrupted. In the case where the vent 26 is only partially separated
from the bottom 29 of the housing 23, current is still allowed to flow
through the cell 24. The safety device 33 ensures full separation of the
vent 26 and current interruption of the cell 24 (such as, e.g., shown in
FIG. 5B).

[0057] According to one exemplary embodiment, the vent 26 may be
configured to open at a much lower internal cell pressure when utilizing
the safety device 33 (as opposed to not using the safety device 33).
Additionally, according to other exemplary embodiments, the force the
safety device 33 exerts on the vent 26 may be adjusted (e.g., by using a
compressive spring having a higher or lower compressive force). With
reference to FIG. 5A, in other embodiments, the current density of the
cell 24 may be increased by increasing a thickness t1 of the annular
fracture groove 54 of the vent 26 (e.g., by having a smaller annular
fracture groove 54 or less of a weakened area). In other words, since the
thickness t1 of the annular fracture groove 54 of the vent 26 is
increased, more current can flow through the vent 26 before deployment.
By having the safety device 33, the vent 26 can still deploy at the
predetermined internal pressure because the compressive force exerted on
the vent 26 by the safety device 33 combines with the force exerted on
the vent 26 by the internal pressure within the cell 24.

[0058] According to an exemplary embodiment, the safety device 33 may be
coated with an electrically insulative material (e.g., a polymer) such
that there is no electrical connection between the cell element 43 or
positive current collector 46 and the safety device 33 (and thus the vent
26).

[0059] Referring now to FIGS. 6-7, the electrochemical cell 24 includes a
second safety device 63 according to another exemplary embodiment. The
safety device 63 is configured to contain a suppressant 67 (e.g., a fire
or flame retardant, or other heat suppressant) to inhibit or limit the
chance of a flame when electrolyte is released from the cell 24 (e.g.,
when the vent 26 is deployed, or when the side of the cell housing is
pierced, e.g., during a vehicle accident). The safety device 63 is in
fluid communication with the vent 26, so that when the vent 26 is
deployed any gases and/or effluent 25 escaping the housing 23 would be
contained by the safety device 63 and mix with suppressant 67 contained
within the safety device 63 in order to inhibit or limit the chance of a
flame when electrolyte is released from the cell 24. According to an
exemplary embodiment, the safety device 63 is filled with the suppressant
67 e.g., through a port or opening (not shown) that is later sealed.

[0060] According to an exemplary embodiment, the suppressant 67 is
contained in a container or housing 65 that is coupled to the outside of
the cell 24. For example, as shown in FIG. 6, the housing 65 includes a
cylindrical side wall 69 having a first end 70 that is coupled (e.g.,
welded, glued, etc.) to the first end 31 of the housing 23 and a second
end 71 that is closed by a bottom 72 to form a chamber 73 (e.g., space,
compartment, container, cavity, etc.). The chamber 73 is configured to
hold the suppressant 67.

[0061] According to another exemplary embodiment, such as shown in FIG. 7,
the side wall 69 of the housing 65 of the safety device 63 is positioned
a predetermined distance d1 away from the cylindrical side wall 27
of the cell 24 and extends along the cylindrical side wall 27 of the cell
24 in a direction generally parallel to the cylindrical side wall 27 of
the cell 24. As such, the suppressant 67 is contained within the housing
65 of the safety device 63 along the outside of the cylindrical side wall
27 of the cell 24.

[0062] As shown in FIG. 7, according to an exemplary embodiment, the side
wall 69 of the housing 65 of the safety device 63 extends generally along
the entire length of the cylindrical side wall 27 of the cell 24.
However, according to other exemplary embodiments, the side wall 69 of
the housing 65 of the safety device 63 may extend along only a portion of
the cylindrical side wall 27 of the cell 24 (e.g., a quarter of the way
along the cylindrical side wall 27 of the cell 24, halfway along the
cylindrical side wall 27 of the cell 24, three-quarters along the
cylindrical side wall 27 of the cell 24, etc.).

[0063] According to an exemplary embodiment, the suppressant 67 is a
material or chemical that behaves as a flame inhibitor or otherwise
limits heat propagation. For example, the suppressant 67 may, in a
physical char-forming process, build up an isolating layer between
condensed and gas phases to stop combustion, and/or may, in a chemical
radical-scavenging process, terminate radical chain reactions of
combustion.

[0064] As an example, dimethyl methyl phosphonate (DMMP) is believed to be
a good free radical inhibitor that captures H. and HO. in the flame zone
to weaken or terminate combustion chain branching reactions. According to
other exemplary embodiments, the suppressant 67 may effectively suppress
flames or heat propagation by other means or mechanisms. According to
still other exemplary embodiments, the suppressant 67 may be
2,4,6-tribromophenol, dibromomethane, tris (2-chloroethyl) phosphate,
triphenylphosphate (TPP), diphenyl phosphate, tris
(2,2,2-tribluoroethyle) phosphate, chloroacetyl chloride,
tribromoethanol, cyclophosphazene, tris (2,2,2-trifluoroethyl) phosphate
(TFP), trimethyl phosphate (TMP), triethyle phosphate (TEP), an organic
phosphorous compound or its halogenated derivatives, other flame
retardant compounds, or combinations thereof (e.g., based on cost,
relative boiling point, etc.).

[0065] According to an exemplary embodiment, when the electrolyte enters
the housing 65 of the safety device 63, the suppressant 67 mixes with the
electrolyte, such as by diffusion or dynamic flow as the electrolyte
enters the housing 65 of the safety device 63. The suppressant 67, as
described above, causes the electrolyte to react with the suppressant 67,
and not with oxygen.

[0066] According to another exemplary embodiment, the vented gases 25 from
the electrochemical cells 24 may include flammable compounds that may
react with oxygen (e.g., oxygen in atmospheric air) to produce a flame
under certain circumstances. To reduce the chance of a flame occurring, a
substance, material, or matter (e.g., a gas, liquid, or solid) may be
provided in the chamber 73 formed by the housing 65 of the safety device
63 to displace the oxygen that would otherwise be in the chamber 73. By
displacing the oxygen, the vented gases 25 will not mix with (and will
not potentially react with) the oxygen.

[0067] According to one exemplary embodiment, such a substance (i.e., the
oxygen displacing material) may be any of the suppressants 67 described
above. According to another exemplary embodiment, the oxygen displacing
material is an inert gas. Because the inert gas is not reactive (under
normal circumstances), the chances of a flame are reduced. Additionally,
because the vented gases 25 are allowed to expand when exiting the
electrochemical cell 24 and entering the chamber 73, the vented gases 25
are allowed to cool. Further, by allowing the vented gases 25 to mix with
the inert gas (which is at a lower temperature than the vented gases),
the vented gases 25 are allowed to cool even more, thus further reducing
the chance of a flame.

[0068] According to one exemplary embodiment, the inert gas is argon.
However, according to other exemplary embodiments, the inert gas may be
any elemental or molecular gas that is not reactive under normal
circumstances (such as, e.g., nitrogen, helium, neon, krypton, xenon,
radon, etc.). According to another exemplary embodiment, the oxygen
displacing material may be a non-flammable foam or other suitable
substance that is non-reactive with the gases and/or effluent 25 that may
be vented from the electrochemical cells 24. According to an exemplary
embodiment, the non-flammable foam may be a hard or soft foam.

[0069] According to an exemplary embodiment, the suppressant 67 may be in
a gas, liquid, or solid form. In any case, the amount of the suppressant
67 within the housing 65 of the safety device 63 is such that the vent 26
of the cell 24 is still allowed to deploy freely into the safety device
63 (i.e., the suppressant 67 does not interfere with the deployment of
the vent 26). According to an exemplary embodiment, the safety device 63
contains approximately 15% suppressant 67 by weight as compared to the
electrolyte contained in the electrochemical cell 24. According to other
embodiments, the safety device 63 contains between approximately 1% and
15% suppressant 67 by weight. Those skilled in the art will readily
recognize that other amounts of suppressant 67 may be provided, whether
measured in an absolute amount or relative to the electrolyte. Further,
those skilled in the art will recognize that, depending on the
suppressant 67 used, providing more suppressant 67 may increase the
electrochemical cell 24's fire retarding ability and overall safety of
the electrochemical cell 24.

[0070] According to another exemplary embodiment, the suppressant 67 may
be contained within a separate container or bag (not shown) within the
housing 65 of the safety device 63. For example, suppressant 67 may be
contained within a low density polyethylene material approximately 1-2
mil thick. According to an exemplary embodiment, the bag material is
configured to melt upon release of the electrolyte from the cell 24 to
release the suppressant 67 therein to mix with the electrolyte. According
to other exemplary embodiments, the bag or container may be a
polyethylene, a polymer, a copolymer, or an aluminum laminate material.

[0071] Those skilled in the art will readily recognize that different bag
configurations, materials, and thicknesses may be chosen depending on
desired characteristics. For example, materials with a lower or higher
melting temperature may be used for the bag or container.

[0072] According to the exemplary embodiments shown in FIGS. 6-7, the
housing 65 of the safety device 63 includes a vent 60. The vent 60 of the
safety device 63 may be configured similar to the vent 26 of the cell 24,
or according to other exemplary embodiments, may be configured
differently. For example, the vent 26 of the cell 24 may be configured to
deploy (i.e., activate, separate, etc.) at a first pressure while the
vent 60 of the safety device 63 is configured to deploy at a second
pressure that is greater than the first pressure. This would allow for
two-stage venting where the first vent 26 (i.e., the vent 26 of the cell
24) would deploy at a first, lower internal pressure of the cell 24 to
interrupt the current flowing through the cell 24. Deployment of the
first vent 26 would also allow the vented electrolyte to mix with the
suppressant 67 contained within the safety device 63. Then, if needed,
the second vent 60 (i.e., the vent 60 of the safety device 63) could
deploy.

[0073] In one exemplary embodiment, the housing 65 of the safety device 63
is made from an inert material, such as polypropylene or low density
polyethylene. According to another exemplary embodiment, the housing 65
of the safety device 63 is made from a metal such as aluminum (or
aluminum alloy), steel, or other suitable material. Those skilled in the
art will recognize that materials, configurations, and manufacturing
methods may be chosen according to desired characteristics, such as
strength, formability of the material, coupling configurations with the
cell 24, etc.

[0074] A particular advantage of the suppressant 67 contained within the
safety device 63 is that the suppressant 67 is separate from the
electrolyte during normal operation of the electrochemical cell 24. This
provides improved performance over electrochemical cells 24 having
electrolytes premixed with a suppressant 67. Further, suppressants 67 may
be used regardless of their electrochemical performance, since the
suppressant 67 is not within the cell 24 during operation of the cell 24.
Suppressants 67 may be chosen instead based on cost, quality,
availability, cell chemistry, or environmental concerns, for example,
rather than electrochemical performance.

[0075] As shown in FIGS. 6-7, the safety device 63 containing the
suppressant 67 may be used in combination with the safety device 33
(e.g., spring, washer, etc.) used to aid in the deployment of the vent 26
of the cell 24. However, according to another exemplary embodiment, the
two safety devices 33, 63 need not be used in combination (i.e., the
safety device 63 containing the suppressant 67 may be used without the
safety device 33 used to deploy the vent 26 of the cell 24).

[0076] Those skilled in the art will readily recognize that the features
disclosed in the embodiments described above may also be incorporated
with different electrochemical cell configurations. For example, the
features may be applied to electrochemical cells 24 having different
configurations or chemistry and/or cells used individually or as part of
a larger system (e.g., within a battery system such as shown in FIGS.
1-4).

[0077] As utilized herein, the terms "approximately," "about,"
"substantially," and similar terms are intended to have a broad meaning
in harmony with the common and accepted usage by those of ordinary skill
in the art to which the subject matter of this disclosure pertains. It
should be understood by those of skill in the art who review this
disclosure that these terms are intended to allow a description of
certain features described and claimed without restricting the scope of
these features to the precise numerical ranges provided. Accordingly,
these terms should be interpreted as indicating that insubstantial or
inconsequential modifications or alterations of the subject matter
described and claimed are considered to be within the scope of the
invention as recited in the appended claims.

[0078] It should be noted that the term "exemplary" as used herein to
describe various embodiments is intended to indicate that such
embodiments are possible examples, representations, and/or illustrations
of possible embodiments (and such term is not intended to connote that
such embodiments are necessarily extraordinary or superlative examples).

[0079] The terms "coupled," "connected," and the like as used herein mean
the joining of two members directly or indirectly to one another. Such
joining may be stationary (e.g., permanent) or moveable (e.g., removable
or releasable). Such joining may be achieved with the two members or the
two members and any additional intermediate members being integrally
formed as a single unitary body with one another or with the two members
or the two members and any additional intermediate members being attached
to one another.

[0080] References herein to the positions of elements (e.g., "top,"
"bottom," "above," "below," etc.) are merely used to describe the
orientation of various elements in the FIGURES. It should be noted that
the orientation of various elements may differ according to other
exemplary embodiments, and that such variations are intended to be
encompassed by the present disclosure.

[0081] It is important to note that the construction and arrangement of
the electrochemical cell 24 having a safety device 33 as shown in the
various exemplary embodiments is illustrative only. Although only a few
embodiments have been described in detail in this disclosure, those
skilled in the art who review this disclosure will readily appreciate
that many modifications are possible (e.g., variations in sizes,
dimensions, structures, shapes and proportions of the various elements,
values of parameters, mounting arrangements, use of materials, colors,
orientations, etc.) without materially departing from the novel teachings
and advantages of the subject matter described herein. For example,
elements shown as integrally formed may be constructed of multiple parts
or elements, the position of elements may be reversed or otherwise
varied, and the nature or number of discrete elements or positions may be
altered or varied. The order or sequence of any process or method steps
may be varied or re-sequenced according to alternative embodiments. Other
substitutions, modifications, changes and omissions may also be made in
the design, operating conditions and arrangement of the various exemplary
embodiments without departing from the scope of the present invention.